Flow-induced alignment of titanium dioxide nanorods in polyolefin tubes for use in catheters

Interventional catheters are the pivotal components of catheter-assisted intervention therapy. However, the inevitable contact and friction between catheters and complex human channels usually lead to severe patient burdens. A fabrication strategy for variable-stiffness catheters based on time-dependent helical flow was developed by regulating the alignment of titanium dioxide (TiO2) nanorods in polyolefin elastomer (POE) catheters. In particular, the uniaxial and off-axial alignments of the TiO2 nanorods were manipulated to adjust the mechanical properties of each section in the POE catheters, where the processing flow pattern was trans-formed from axial to helical. To achieve the desired performance in practical applications, two catheters with a programmable helix angle of embedded TiO2 nanorods along the axial direction were designed. Correspond-ingly, the as-designed catheters displayed remarkably reduced interventional loads (e.g., a maximum reduction of 49.3% and 39.7% in single-and multi-curvature channels, respectively) and an enhancement of 50% in rotation synchronization, indicating promising potential for application in catheter-assisted interventional therapy. This study proposes an effective structuring design strategy for composed catheters with variable-stiffness segments that can be extended to all interventional catheter production techniques.